1. Field of Inventions
The present inventions relate generally to ambulatory infusion devices.
2. Description of the Related Art
Ambulatory infusion devices, such as implantable infusion devices and externally carried infusion devices, have been used to provide a patient with a medication or other substance (collectively “infusible substance”) and frequently include a reservoir and a pump. The reservoir is used to store the infusible substance and, in some instances, implantable infusion devices are provided with a fill port that allows the reservoir to be transcutaneously filled (and/or re-filled) with a hypodermic needle. The reservoir is coupled to the pump, which is in turn connected to an outlet port. A catheter, which has an at least one outlet at the target body region, may be connected to the outlet port. As such, infusible the reservoir may be transferred from the reservoir to the target body region by way of the pump and catheter.
There are a number of blockage-related issues that can prevent an ambulatory infusion device from functioning properly. Catheters, for example, may become partially or completely blocked (collectively “blocked”) by the formation of tissue at the catheter outlet. Catheters may also develop kinks that can partially or completely block fluid flow. Partial blockages can prevent the patient from receiving the intended dosage of the infusible substance, while complete blockages will prevent any of the infusible substance from reaching the patient.
The present inventors have determined that conventional methods of detecting blockages are susceptible to improvement. For example, some conventional methods of detecting blockages rely on catheter pressure measurements and, more specifically, on measured increases in catheter pressure. The present inventors have determined that conventional pressure-based methods of detecting blockages can be inaccurate in that they may determine that a blockage is present when in fact no blockage is present (referred to herein as “a false blockage determination”) as a result of changes in environmental pressure.